Center locating punch



Sept.-9, 1941. F. H. MUELLER CENTER LOCATING PUNCH Filed Jan. 26, 1940ll l'llll Patented Sept. 9, 1941 UNITED STATES TENT OFFICE CENTERLOCATING PUNCH Frank H. Mueller, Decatur, IlL, assignor t Mueller 00.,Decatur, 111., a corporation of Illinois 1 Claim.

This invention relates to means for forming in a body a centeringindentation for a drill which must be introduced to working positionthrough a tubular member or fitting which is secured at one end to thebody and is open at the other, the object being to assure that theindentation is exactly on the axis of the fitting. It is customary, forexample, to weld a T to a main and then to introduce a drill through theT to drill a communicating opening in the wall of the main.I-Ieretofore, there has been considerable difliculty in starting thedrill exactly on the line of the T axis. It is such difiiculty which thepresent invention has as its object to overcome. Preferred means forachieving this object are shown in the accompanying drawing, withreference to which description of the invention will be made.

In the drawing,

Figure 1 is an axial section of a center locating punch in accordancewith the invention and of a T to which the punch is operatively applied,a main to which the T is Welded being shown in part in transversesection, and

Figure 2 is a top or plan view of the new punch.

Referring to the drawing, reference numeral 5 designates a main to whichthe cross portion of a T 6 is welded at one end by a fillet l with itsaxis substantially normal to the wall of the main. At its upper, orouter, open end the T is internally and externally thickened andprovided with internal and external threads.

Reference numeral 8 designates a punch having an elongated cylindricalstem portion 9 provided at one end with an exactly centered point l0 andat the other with a head ll. Reference numeral !2 designate a sleevehaving a bore in which the stem portion 9 of the punch has a free butclose sliding fit so as to be accurately guided for axial movement. Atone extremity the sleeve has a portion l3 engageable by a turning tooland for this purpose the portion I3 may be hexagonal, as shown. Beneathportion l3 are three externally threaded portions l4, l5 and iii ofstepped-down dilferent diameter, the portion It being of a size to beengaged with the internal threads of the T. Portions I 4 and iii aresimilarly engageable in the threaded portions of appropriately sized Ts.The threaded portions l3, I4 and I5, which are, of course, accuratelycoaxial with the sleeve bore, are respectively surmounted by shouldersI'!, l8 and I9 which are normal to the bore axis. The stem ,9 of thepunch is somewhat longer than the sleeve bore when, as here shown, thepunch includes a head.

In the use of the tool in connection with a T of the size shown, theportion l6 of the sleeve is threaded into the end of the T preferablyuntil shoulder l9 abuts the T end. Normally the threads will accuratelycenter the sleeve bore with respect to the T, but in case of wornthreads, the shoulder H3, in engagement with the T end, will supplementthis function. With the sleeve thus engaged with the T, it extends asubstantial distance toward the main 5. In the present instance, it isshown terminating far enough away from the main so that when thethreaded portion M is engaged with a T of larger diameter but of thesame length as that shown, the inner end of the sleeve will still beclear of the wall of the main. With the sleeve applied as described, thepunch may be introduced and struck to form an indentation in the wall ofthe main. The indentation will be exactly on the axis of the fitting,since the elongated sleeve rigidly positions the punch stem. The punchstem, as shown, is of substantially smaller diameter than the innerdiameter of the T passage, so that the sleeve walls can be made ofadequate thickness and yet be spaced somewhat from the inner walls ofthe T below the interengaged threaded portions.

It will be understood that the invention is not limited to the precisedetails described, and that accordingly I do not limit myself in theserespects except as in the following claim.

I claim:

Means for forming in a main to be drilled a drill centering depressionon the axis of a tubular fitting which ha one end secured against saidmain and is open at the other end, said other end being threaded, saidmeans comprising a center punch whose diameter is substantially lessthan the inner diameter of the fitting, and a sleeve in which said punchhas a close sliding fit, said sleeve having a threaded portionengageable with the threaded end of said fitting to position the sleevecoaxially relative to the latter, said sleeve having a portion whichwhen the sleeve is engaged with the fitting extends into adjacency tothe main to provide an extended axial guide for said punch, said sleeveconstituting the sole guide means for the punch and the punch Beingremovable with the sleeve from said fiting.

FRANK H. MUELLER.

